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Supplemental instruction Nervous system (Instro.) Picture from http://en.wikipedia.org/wiki/Neuron Designed by Pyeongsug Kim ©2010 [email protected] Nervous System Two types of cells in nervous tissue: Neurons and Supporting cells (glial cells in CNS) Central nervous system (CNS) = brain and spinal cord Peripheral nervous system (PNS) = cranial and spinal nerves (all nervous tissue outside the CNS) Designed by Pyeongsug Kim, ©2010 www.science-i.com Cranial nerve (PNS) Designed by Pyeongsug Kim, ©2010 www.science-i.com A B C H F(Pink) G D E A:Dendrites B:Nucleus C: Axon hillcock D:Cell body E:Axon F(Pink):Myelin H: Schwann cell G: Axon terminal D:Cell body __________ __________ A:Dendrites C:__________ Axon hillcock __________ E:Axon F(Pink):Myelin __________ H:Schwann cell Nutritional center; nucleus and organelles. transmit electrical impulses to the cell body. nerve impulses originate there. transmits impulse away from the cell body. is wrapped around the axon Designed by Pyeongsug Kim, ©2010 www.science-i.com In periphery, myelin is produced by Schwann cells. In CNS, it is produced by oligodendrocytes. Schwann cells and oligodendrocytes are Supporting cells. Designed by Pyeongsug Kim, ©2010 www.science-i.com A How many type of cells are seen?Two: Neuron, Schwann cell What is the unmyelinated part A? Node of Ranvier What does myelin do? Advantage? Electrically insulates axon. ;improves the conduction speed of nerve impulses, enabling fast reactions Myelinated axons conduct nervous impulses more rapidly than unmyelinated. Designed by Pyeongsug Kim, ©2010 www.science-i.com Structural Classes of Neurons Pseudounipolar _______________ -One process -Dendrites act as receptors -Axon leads to brain or spinal cord -e.g. Most sensory neurons Bipolar _______________ -Dendrites and axon arise from apposite ends of cell body. -e.g. Retina Multipolar _______________ -Dendrites and axon arise from apposite ends of cell body. -e.g. Motor neuron, Interneuron Designed by Pyeongsug Kim, ©2010 www.science-i.com Function of Nervous system 1) Senses _______ (such as sight, touch, stimuli taste, etc.) 2) Formulates a response to the stimuli : perceptions, thoughts, and reflexes CNS usually in the ______. 3) Transmits signals rapidly between body parts :Sense organs CNS :CNS the muscles (Response) Designed by Pyeongsug Kim, ©2010 www.science-i.com What are the two supporting cells (glial cells) in the PNS? What they do? Schwann cells ______________ -form myelin sheaths around peripheral axons Satellite cells ______________ -supply nutrients, some structural function. -act as protective, cushioning cells. -lining the exterior surface of neurons; -surround neuron cell bodies within ganglia * Ganglia = collection of cell bodies. Designed by Pyeongsug Kim, ©2010 www.science-i.com What are the four supporting cells in the CNS? Astrocyte, Ependymal cells, Oligodendrocyte, & Microglia Designed by Pyeongsug Kim, ©2010 www.science-i.com In the CNS A E B F C Fluid! D G A: Capillary B: Astrocyte D: Cerebral spinal fluid F: Oligodendrocyte C: Ependymal cells E: Neurons G: Microglia What are B, C, F, and G? Supporting(glial) cells Designed by Pyeongsug Kim, ©2010 www.science-i.com A: Capillary B: Astrocyte D: Cerebral spinal fluid F: Oligodendrocyte C: Ependymal cells E: Neurons G: Microglia All but not A & E ______________are glial cell in CNS B: Astrocyte ______________are common glial cell in CNS B: Astrocyte ______________form blood-brain barrier B: Astrocyte ______________Help with ion uptake and help move glucose from blood to brain. C: Ependymal cells ______________Neural stem cells. G: Microglia ______________Immune response in NS, recognizing infectious agents Designed by Pyeongsug Kim, ©2010 www.science-i.com In CNS, Some have myelinated part. Other have unmyelinated part. White matter (myelinated part) Gray matter (unmyelinated part) (Cell bodies and dendrites are gray matter) Designed by Pyeongsug Kim, ©2010 www.science-i.com ________________ Blood-Brain Barrier -Capillary specializations in the brain -Do not allowed most nutrients and other molecules in the blood to exit. astrocytes help with ion uptake and help move glucose from blood to - But, __________ brain and form blood-brain barrier Designed by Pyeongsug Kim, ©2010 www.science-i.com ___________ Interneuron located entirely within CNS, integrates functions in CNS Sensory (from sensory receptor to CNS) What are the two types of motor neuron? Somatic stimulates skeletal muscles _________ Autonomic affects smooth and cardiac muscle, also glandular _________ secretion. Designed by Pyeongsug Kim, ©2010 www.science-i.com Nerve ___________ Ganglion ___________ ___________ Nucleus Tract ___________ bundle of axons bundle of nerve cell bodies outside of CNS bundle of nerve cell bodies within CNS connects regions of CNS Designed by Pyeongsug Kim, ©2010 www.science-i.com neurons, Interneuron, & motor neuron There are three neuron types Sensory _____________________________________ Designed by Pyeongsug Kim, ©2010 www.science-i.com Interneurons -association neurons -(PNS/CNS) neuron CNS Sensory neurons -afferent neurons(to the CNS) -(PNS/CNS) neuron -to neurons in the CNS -stimulated by ___________. sense stimuli Motor neurons -efferent neurons (from the CNS) -(PNS/CNS) neuron -to muscles or glands -stimulated by ___________. interneurons Designed by Pyeongsug Kim, ©2010 www.science-i.com ______ Nerve -Bundle of axons in the PNS -Wrapped by _______________. connective tissue -Most mixed nerves: ______________________. sensory and motor neurons Cranial nerves ________________ -Nerves that connect to the CNS in the head -(PNS/CNS) ________________ Spinal nerves -Nerves that connect to the CNS in the spine -(PNS/CNS) Designed by Pyeongsug Kim, ©2010 www.science-i.com Cell membrane is more pearmeable ( K+ than Na+ / Na+ than K+) . _________________ Equilibrium potential voltage across membrane due to only 1 ion where electrical and diffusion forces are equal and opposite. ie/ K+ =_______ -90mV , Na+ = _____ 60mV Resting membrane potential (RMP) ________________________ -Not producing impulses, -Around _______ -70mV -K+ drives most of RMP because it is quite permeable. Designed by Pyeongsug Kim, ©2010 www.science-i.com Choose K+, Na+, Cl-, Mg2+ K+ is very permeable and is high inside cell. The inside cell ___ is large (negatively/positively) charged molecules inside the cell. ___ N+ moves out faster than ___ K+ moves in. What is the protein transport on the membrane contributes to the resting membrane potential?Na+/K+ pump Designed by Pyeongsug Kim, ©2010 www.science-i.com _______________ Action potential -The electrical nerve signal that travels through the axon. -” ALL or NONE!” Designed by Pyeongsug Kim, ©2010 www.science-i.com Voltage-gated sodium channels are found all along the axon. Potassium channels are found near each voltage-gated sodium channel. Threshold voltage -The voltage enough to open the VGchannel -50 ~55mv Designed by Pyeongsug Kim, ©2010 www.science-i.com 1)Resting membrane 2) Membrane potential reaches at threshold. 3) Na+-VG channel open 4) Na+-VG channel close 5) K+-VG channel open 6) K+-VG channel close 7) Na+/K+ pump restore balance of the ions. Designed by Pyeongsug Kim, ©2010 www.science-i.com Define “resting membrane potential.” How many mV is it? A potential difference across the membrane. -70mV *Choose Depolarization, Repolarization, & Hyperpolarization. ___________ back to the resting potential Repolarization ___________ positive charges to flow into Depolarization the cell. Depolarization ___________ potential difference approaches zero Hyperpolarization ___________ potential difference increases by negative charges enter cell Designed by Pyeongsug Kim, ©2010 www.science-i.com *Choose depolarization, repolarization, & hyperpolarization, threshold, K+, Na+. Na+ The resting cell is more permeable to K+ __ than __. The leakage channels for K+ are always (open/closed) at the resting cell. There are VG channels for K+ and Na+, which are always (open/closed) at resting cell. threshold by depolarization At ________ ________, VG channels forNa+ __ are open and membrane becomes permeable toNa+ __, and Na+ __ can diffuse into cell causing depolarization _________.(positive feedback) ;causes a rapid change in MP from –70 to +30 mV *VG:Votage-gated Designed by Pyeongsug Kim, ©2010 www.science-i.com *Choose depolarization, repolarization, & hyperpolarization, threshold, K+, Na+. Just before VG channels for Na+, VG channels for__ K+,are open and K+, __ diffuses out of the cell causing __________, repolarization which repolarizes axon back to the resting membrane potential. How does the cell return back to the resting membrane potential? Na/K pumps restore balance of the ions. *VG:Votage-gated Designed by Pyeongsug Kim, ©2010 www.science-i.com Action potential The electrical nerve signal that travels through the axon. Action potention is formed by rapid depolarization of the membrane by (Na+/K+/Mg2+) (influx/efflux); followed by rapid repolarization by (Na+/K+/Mg2+) (influx/efflux). Designed by Pyeongsug Kim, ©2010 www.science-i.com Refractory period ______________ When a region of the axon has started to depolarize, it must fully complete its entire depolarization sequence before a new action potential can begin refractory period called the _______________. Designed by Pyeongsug Kim, ©2010 www.science-i.com Review for de-, re-,and Hyperpolarization K+ Na+ Na+ K+ Resting membrane Depolarization Hyperpolarization, but In action potential, repolarization Designed by Pyeongsug Kim, ©2010 www.science-i.com Hyperpolarization Strength effect = Action ____________ potential frequency Stronger stimuli stimulate more and more _______. Axons As more action potentials are stimulated, their amplitude (increases/decreases/does not change). Increased stimulus intensity causes (more/less) APs to be fired. Designed by Pyeongsug Kim, ©2010 www.science-i.com Ligand-Receptor interaction -interaction between a molecule (ligand) and a protein on or within a target cell (receptor). Ligands ~ Neurotransmitter, hormones… Receptors ~ Neurotransmitter receptors, hormone receptors, ligand-gated channel… (specific!) Designed by Pyeongsug Kim, ©2010 www.science-i.com __________is a connection between a Synapse neuron, called __________, presynaptic and an another cell, called __________. postsynaptic There are a few _________ electrical synapse in nervous system, in smooth muscle and in heart gap junctions. Most are __________ chemical synapses. Synaptic transmission at chemical synapses is via _______________. neurotransmitters Designed by Pyeongsug Kim, ©2010 www.science-i.com A : Neuron (Presynaptic) B : Neuron or cells (Postsynaptic) C: Neurotransmitter(NT) C 1. Mitochondria 2. Synaptic vesicle 3. Autoreceptor 4. Synaptic cleft 5. NT receptor 6. Calcium Channel 7. release NT by___________ exocytosis 8. NT re-uptake pump Chemical Synapse! Designed by Pyeongsug Kim, ©2010 www.science-i.com Synaptic Transmission 1.Action potentials reach at the axon terminal. 2.VG-Ca2+ channels open. 3. Ca2+ activates calmodulin. 4. Calmodulin activates a protein kinase. 5. Protein kinase promote fusion and exocytosis of vesicles. Designed by Pyeongsug Kim, ©2010 www.science-i.com Depolarizing channels cause ___________________________ EPSPs (excitatory postsynaptic potentials) Hyperpolarizing channels cause __________ IPSPs (inhibitory postsynaptic potentials) Designed by Pyeongsug Kim, ©2010 www.science-i.com EPSPs and IPSPs summate. if membrane potential in postsynaptic cell reaches threshold at the axon hillock, a new AP is generated. if not, no AP occur. Designed by Pyeongsug Kim, ©2010 www.science-i.com Acetylcholine (ACh) is most widely used as ______ NT and has _________ nicotinic and ___________ muscarinic receptor. ________________ nicotinic muscarinic ________________ Designed by Pyeongsug Kim, ©2010 www.science-i.com Nicotinic ACh Receptor Muscarinic ACh Receptor Where are they? Where do they do? Some glands Designed by Pyeongsug Kim, ©2010 www.science-i.com